Medical devices are used to deliver therapy to patients to treat a variety of symptoms or conditions, and may be implantable or external. An implantable neurostimulator, for example, may treat symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, incontinence, or gastroparesis. The implantable medical device delivers neurostimulation therapy via one or more leads that include electrodes located proximate to the spinal cord, pelvic nerves, or stomach, or within the brain of a patient. In general, the implantable medical device delivers neurostimulation therapy in the form of electrical pulses.
A clinician selects values for a number of programmable parameters in order to define the neurostimulation therapy to be delivered to a patient. For example, the clinician may select an amplitude, which may be a current or voltage amplitude, and pulse width for a stimulation waveform to be delivered to the patient, as well as a rate at which the pulses are to be delivered to the patient. In addition, the clinician also selects particular electrodes within an electrode set to be used to deliver the pulses, and the polarities of the selected electrodes.
The clinician uses a clinician programmer to program the parameters into the implantable medical device. The implantable medical device may store multiple programs, however, which may be selected by the patient using a patient programmer. The patient may select different programs to modify therapy delivered by the implantable medical devices, e.g., to achieve greater pain relief. Different programs may be appropriate for different times of day or different physical activities or postures.
The patient programmer communicates with the implantable medical device to modify programs using radio frequency (RF) telemetry. For this reason, the patient programmer includes an external antenna with an RF telemetry head for placement on the patient's body at a position near the implantable medical device. The patient programmer is typically designed as a mobile device that may be carried by the patient throughout the course of the day. For example, the patient programmer may be a handheld device, and typically is powered by batteries within the device.